Quantitative Analysis of Tooth Mineral Content by High Resolution Micro-computed Tomography

Teeth and bones are highly mineralized tissues containing inorganic minerals such as calcium phosphate, and a growing number of evidences show that their mineral content is associated with many diseases. Although the quantification of mineral contents by micro-computed tomography(micro- CT) has been used in diagnosis and evaluation for treating bone diseases, its application for teeth diseases has not been well established. In this study, we attempted to estimate a usefulness of a high-resolution micro-CT in analysis of human teeth. The teeth were scanned by using the Skyscan 1172 micro-CT. In order to measure tooth mineral content, beam hardening effect of the machine was corrected with a radiopaque iodinecontaining substance, iodoacetamide. Under the maximum resolution of 6.6 µm, X-ray densities in teeth and hydroxyapatite standards were obtained with Hounsfield unit (HU), and they were then converted to an absolute mineral concentration by a CT Analyzer software. In enamel layer of cusp area, the mean mineral concentration was about 2.14 mg/mm³ and there was a constant mineral concentration gradient from the enamel surface to the dentinoenamel junction. In the dentin of middle 1/3 of tooth, the mean mineral concentration was approximately 1.27 mg/mm³ and there was a constant mineral concentration gradient from the outer of root to the pulp side, ranging from 1.3 to 1.06 mg/mm³. In decay region of dentin, the mineral content was gradually decreased from the intact inner side to the decayed surface. These results suggest that high-resolution micro-CT can be as a useful tool for non-invasive measurement of mineral concentration in teeth.

A Retrospective Epidemiologic Analysis of Elderly Burn Patients at Hanil General Hospital

PURPOSE: This study aims to analyse the epidemiologic characteristics of burn in the elderly and to discusses a possible prevention program for this population. METHODS: A retrospective review of all medical records of elderly patients (above 60 years old) admitted with burns to the burn center of the Hanil General Hospital from January 1996 to December 2007 was carried out. Patient demographics, etiology, extent, and type of burn, seasonal variation, and mortality rates were reviewed. RESULTS: A total of 537 elderly patients (mean age of 69.8 years, median age of 68 years, range 60~97 years) was admitted. The gender ratio of the patients was 1:.5 with 217 men and 320 women. The most common causes were scald burn (44.9%) and flame burn (35.4%). The average total body area burned was 13.5% (range 0~95%). Twenty six patients (4.8%) died. CONCLUSION: In elderly patients, scald burns are more common in women but flame burns are more common in men. The mortality rate is higher in flame burns and men